1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * NET3: Implementation of the ICMP protocol layer. 4 * 5 * Alan Cox, <alan@lxorguk.ukuu.org.uk> 6 * 7 * Some of the function names and the icmp unreach table for this 8 * module were derived from [icmp.c 1.0.11 06/02/93] by 9 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting. 10 * Other than that this module is a complete rewrite. 11 * 12 * Fixes: 13 * Clemens Fruhwirth : introduce global icmp rate limiting 14 * with icmp type masking ability instead 15 * of broken per type icmp timeouts. 16 * Mike Shaver : RFC1122 checks. 17 * Alan Cox : Multicast ping reply as self. 18 * Alan Cox : Fix atomicity lockup in ip_build_xmit 19 * call. 20 * Alan Cox : Added 216,128 byte paths to the MTU 21 * code. 22 * Martin Mares : RFC1812 checks. 23 * Martin Mares : Can be configured to follow redirects 24 * if acting as a router _without_ a 25 * routing protocol (RFC 1812). 26 * Martin Mares : Echo requests may be configured to 27 * be ignored (RFC 1812). 28 * Martin Mares : Limitation of ICMP error message 29 * transmit rate (RFC 1812). 30 * Martin Mares : TOS and Precedence set correctly 31 * (RFC 1812). 32 * Martin Mares : Now copying as much data from the 33 * original packet as we can without 34 * exceeding 576 bytes (RFC 1812). 35 * Willy Konynenberg : Transparent proxying support. 36 * Keith Owens : RFC1191 correction for 4.2BSD based 37 * path MTU bug. 38 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are 39 * valid (RFC 1812). 40 * Andi Kleen : Check all packet lengths properly 41 * and moved all kfree_skb() up to 42 * icmp_rcv. 43 * Andi Kleen : Move the rate limit bookkeeping 44 * into the dest entry and use a token 45 * bucket filter (thanks to ANK). Make 46 * the rates sysctl configurable. 47 * Yu Tianli : Fixed two ugly bugs in icmp_send 48 * - IP option length was accounted wrongly 49 * - ICMP header length was not accounted 50 * at all. 51 * Tristan Greaves : Added sysctl option to ignore bogus 52 * broadcast responses from broken routers. 53 * 54 * To Fix: 55 * 56 * - Should use skb_pull() instead of all the manual checking. 57 * This would also greatly simply some upper layer error handlers. --AK 58 */ 59 60 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 61 62 #include <linux/module.h> 63 #include <linux/types.h> 64 #include <linux/jiffies.h> 65 #include <linux/kernel.h> 66 #include <linux/fcntl.h> 67 #include <linux/socket.h> 68 #include <linux/in.h> 69 #include <linux/inet.h> 70 #include <linux/inetdevice.h> 71 #include <linux/netdevice.h> 72 #include <linux/string.h> 73 #include <linux/netfilter_ipv4.h> 74 #include <linux/slab.h> 75 #include <net/flow.h> 76 #include <net/snmp.h> 77 #include <net/ip.h> 78 #include <net/route.h> 79 #include <net/protocol.h> 80 #include <net/icmp.h> 81 #include <net/tcp.h> 82 #include <net/udp.h> 83 #include <net/raw.h> 84 #include <net/ping.h> 85 #include <linux/skbuff.h> 86 #include <net/sock.h> 87 #include <linux/errno.h> 88 #include <linux/timer.h> 89 #include <linux/init.h> 90 #include <linux/uaccess.h> 91 #include <net/checksum.h> 92 #include <net/xfrm.h> 93 #include <net/inet_common.h> 94 #include <net/ip_fib.h> 95 #include <net/l3mdev.h> 96 #include <net/addrconf.h> 97 #include <net/inet_dscp.h> 98 #define CREATE_TRACE_POINTS 99 #include <trace/events/icmp.h> 100 101 /* 102 * Build xmit assembly blocks 103 */ 104 105 struct icmp_bxm { 106 struct sk_buff *skb; 107 int offset; 108 int data_len; 109 110 struct { 111 struct icmphdr icmph; 112 __be32 times[3]; 113 } data; 114 int head_len; 115 struct ip_options_data replyopts; 116 }; 117 118 /* An array of errno for error messages from dest unreach. */ 119 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ 120 121 const struct icmp_err icmp_err_convert[] = { 122 { 123 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ 124 .fatal = 0, 125 }, 126 { 127 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ 128 .fatal = 0, 129 }, 130 { 131 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, 132 .fatal = 1, 133 }, 134 { 135 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ 136 .fatal = 1, 137 }, 138 { 139 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ 140 .fatal = 0, 141 }, 142 { 143 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ 144 .fatal = 0, 145 }, 146 { 147 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ 148 .fatal = 1, 149 }, 150 { 151 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ 152 .fatal = 1, 153 }, 154 { 155 .errno = ENONET, /* ICMP_HOST_ISOLATED */ 156 .fatal = 1, 157 }, 158 { 159 .errno = ENETUNREACH, /* ICMP_NET_ANO */ 160 .fatal = 1, 161 }, 162 { 163 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ 164 .fatal = 1, 165 }, 166 { 167 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ 168 .fatal = 0, 169 }, 170 { 171 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ 172 .fatal = 0, 173 }, 174 { 175 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ 176 .fatal = 1, 177 }, 178 { 179 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ 180 .fatal = 1, 181 }, 182 { 183 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ 184 .fatal = 1, 185 }, 186 }; 187 EXPORT_SYMBOL(icmp_err_convert); 188 189 /* 190 * ICMP control array. This specifies what to do with each ICMP. 191 */ 192 193 struct icmp_control { 194 enum skb_drop_reason (*handler)(struct sk_buff *skb); 195 short error; /* This ICMP is classed as an error message */ 196 }; 197 198 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; 199 200 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk); 201 202 /* Called with BH disabled */ 203 static inline struct sock *icmp_xmit_lock(struct net *net) 204 { 205 struct sock *sk; 206 207 sk = this_cpu_read(ipv4_icmp_sk); 208 209 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 210 /* This can happen if the output path signals a 211 * dst_link_failure() for an outgoing ICMP packet. 212 */ 213 return NULL; 214 } 215 sock_net_set(sk, net); 216 return sk; 217 } 218 219 static inline void icmp_xmit_unlock(struct sock *sk) 220 { 221 sock_net_set(sk, &init_net); 222 spin_unlock(&sk->sk_lock.slock); 223 } 224 225 /** 226 * icmp_global_allow - Are we allowed to send one more ICMP message ? 227 * @net: network namespace 228 * 229 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec. 230 * Returns false if we reached the limit and can not send another packet. 231 * Works in tandem with icmp_global_consume(). 232 */ 233 bool icmp_global_allow(struct net *net) 234 { 235 u32 delta, now, oldstamp; 236 int incr, new, old; 237 238 /* Note: many cpus could find this condition true. 239 * Then later icmp_global_consume() could consume more credits, 240 * this is an acceptable race. 241 */ 242 if (atomic_read(&net->ipv4.icmp_global_credit) > 0) 243 return true; 244 245 now = jiffies; 246 oldstamp = READ_ONCE(net->ipv4.icmp_global_stamp); 247 delta = min_t(u32, now - oldstamp, HZ); 248 if (delta < HZ / 50) 249 return false; 250 251 incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec) * delta / HZ; 252 if (!incr) 253 return false; 254 255 if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) { 256 old = atomic_read(&net->ipv4.icmp_global_credit); 257 do { 258 new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst)); 259 } while (!atomic_try_cmpxchg(&net->ipv4.icmp_global_credit, &old, new)); 260 } 261 return true; 262 } 263 EXPORT_SYMBOL(icmp_global_allow); 264 265 void icmp_global_consume(struct net *net) 266 { 267 int credits = get_random_u32_below(3); 268 269 /* Note: this might make icmp_global.credit negative. */ 270 if (credits) 271 atomic_sub(credits, &net->ipv4.icmp_global_credit); 272 } 273 EXPORT_SYMBOL(icmp_global_consume); 274 275 static bool icmpv4_mask_allow(struct net *net, int type, int code) 276 { 277 if (type > NR_ICMP_TYPES) 278 return true; 279 280 /* Don't limit PMTU discovery. */ 281 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 282 return true; 283 284 /* Limit if icmp type is enabled in ratemask. */ 285 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask))) 286 return true; 287 288 return false; 289 } 290 291 static bool icmpv4_global_allow(struct net *net, int type, int code, 292 bool *apply_ratelimit) 293 { 294 if (icmpv4_mask_allow(net, type, code)) 295 return true; 296 297 if (icmp_global_allow(net)) { 298 *apply_ratelimit = true; 299 return true; 300 } 301 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 302 return false; 303 } 304 305 /* 306 * Send an ICMP frame. 307 */ 308 309 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, 310 struct flowi4 *fl4, int type, int code, 311 bool apply_ratelimit) 312 { 313 struct dst_entry *dst = &rt->dst; 314 struct inet_peer *peer; 315 struct net_device *dev; 316 bool rc = true; 317 318 if (!apply_ratelimit) 319 return true; 320 321 /* No rate limit on loopback */ 322 rcu_read_lock(); 323 dev = dst_dev_rcu(dst); 324 if (dev && (dev->flags & IFF_LOOPBACK)) 325 goto out; 326 327 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 328 l3mdev_master_ifindex_rcu(dev)); 329 rc = inet_peer_xrlim_allow(peer, 330 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit)); 331 out: 332 rcu_read_unlock(); 333 if (!rc) 334 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST); 335 else 336 icmp_global_consume(net); 337 return rc; 338 } 339 340 /* 341 * Maintain the counters used in the SNMP statistics for outgoing ICMP 342 */ 343 void icmp_out_count(struct net *net, unsigned char type) 344 { 345 ICMPMSGOUT_INC_STATS(net, type); 346 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); 347 } 348 349 /* 350 * Checksum each fragment, and on the first include the headers and final 351 * checksum. 352 */ 353 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, 354 struct sk_buff *skb) 355 { 356 struct icmp_bxm *icmp_param = from; 357 __wsum csum; 358 359 csum = skb_copy_and_csum_bits(icmp_param->skb, 360 icmp_param->offset + offset, 361 to, len); 362 363 skb->csum = csum_block_add(skb->csum, csum, odd); 364 if (icmp_pointers[icmp_param->data.icmph.type].error) 365 nf_ct_attach(skb, icmp_param->skb); 366 return 0; 367 } 368 369 static void icmp_push_reply(struct sock *sk, 370 struct icmp_bxm *icmp_param, 371 struct flowi4 *fl4, 372 struct ipcm_cookie *ipc, struct rtable **rt) 373 { 374 struct sk_buff *skb; 375 376 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param, 377 icmp_param->data_len+icmp_param->head_len, 378 icmp_param->head_len, 379 ipc, rt, MSG_DONTWAIT) < 0) { 380 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS); 381 ip_flush_pending_frames(sk); 382 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { 383 struct icmphdr *icmph = icmp_hdr(skb); 384 __wsum csum; 385 struct sk_buff *skb1; 386 387 csum = csum_partial_copy_nocheck((void *)&icmp_param->data, 388 (char *)icmph, 389 icmp_param->head_len); 390 skb_queue_walk(&sk->sk_write_queue, skb1) { 391 csum = csum_add(csum, skb1->csum); 392 } 393 icmph->checksum = csum_fold(csum); 394 skb->ip_summed = CHECKSUM_NONE; 395 ip_push_pending_frames(sk, fl4); 396 } 397 } 398 399 /* 400 * Driving logic for building and sending ICMP messages. 401 */ 402 403 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) 404 { 405 struct rtable *rt = skb_rtable(skb); 406 struct net *net = dev_net_rcu(rt->dst.dev); 407 bool apply_ratelimit = false; 408 struct ipcm_cookie ipc; 409 struct flowi4 fl4; 410 struct sock *sk; 411 __be32 daddr, saddr; 412 u32 mark = IP4_REPLY_MARK(net, skb->mark); 413 int type = icmp_param->data.icmph.type; 414 int code = icmp_param->data.icmph.code; 415 416 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb)) 417 return; 418 419 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 420 local_bh_disable(); 421 422 /* is global icmp_msgs_per_sec exhausted ? */ 423 if (!icmpv4_global_allow(net, type, code, &apply_ratelimit)) 424 goto out_bh_enable; 425 426 sk = icmp_xmit_lock(net); 427 if (!sk) 428 goto out_bh_enable; 429 430 icmp_param->data.icmph.checksum = 0; 431 432 ipcm_init(&ipc); 433 ipc.tos = ip_hdr(skb)->tos; 434 ipc.sockc.mark = mark; 435 daddr = ipc.addr = ip_hdr(skb)->saddr; 436 saddr = fib_compute_spec_dst(skb); 437 438 if (icmp_param->replyopts.opt.opt.optlen) { 439 ipc.opt = &icmp_param->replyopts.opt; 440 if (ipc.opt->opt.srr) 441 daddr = icmp_param->replyopts.opt.opt.faddr; 442 } 443 memset(&fl4, 0, sizeof(fl4)); 444 fl4.daddr = daddr; 445 fl4.saddr = saddr; 446 fl4.flowi4_mark = mark; 447 fl4.flowi4_uid = sock_net_uid(net, NULL); 448 fl4.flowi4_dscp = ip4h_dscp(ip_hdr(skb)); 449 fl4.flowi4_proto = IPPROTO_ICMP; 450 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev); 451 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4)); 452 rt = ip_route_output_key(net, &fl4); 453 if (IS_ERR(rt)) 454 goto out_unlock; 455 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 456 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt); 457 ip_rt_put(rt); 458 out_unlock: 459 icmp_xmit_unlock(sk); 460 out_bh_enable: 461 local_bh_enable(); 462 } 463 464 /* 465 * The device used for looking up which routing table to use for sending an ICMP 466 * error is preferably the source whenever it is set, which should ensure the 467 * icmp error can be sent to the source host, else lookup using the routing 468 * table of the destination device, else use the main routing table (index 0). 469 */ 470 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb) 471 { 472 struct net_device *dev = skb->dev; 473 const struct dst_entry *dst; 474 475 if (dev) 476 return dev; 477 dst = skb_dst(skb); 478 return dst ? dst_dev(dst) : NULL; 479 } 480 481 static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4, 482 struct sk_buff *skb_in, 483 const struct iphdr *iph, __be32 saddr, 484 dscp_t dscp, u32 mark, int type, 485 int code, struct icmp_bxm *param) 486 { 487 struct net_device *route_lookup_dev; 488 struct dst_entry *dst, *dst2; 489 struct rtable *rt, *rt2; 490 struct flowi4 fl4_dec; 491 int err; 492 493 memset(fl4, 0, sizeof(*fl4)); 494 fl4->daddr = (param->replyopts.opt.opt.srr ? 495 param->replyopts.opt.opt.faddr : iph->saddr); 496 fl4->saddr = saddr; 497 fl4->flowi4_mark = mark; 498 fl4->flowi4_uid = sock_net_uid(net, NULL); 499 fl4->flowi4_dscp = dscp; 500 fl4->flowi4_proto = IPPROTO_ICMP; 501 fl4->fl4_icmp_type = type; 502 fl4->fl4_icmp_code = code; 503 route_lookup_dev = icmp_get_route_lookup_dev(skb_in); 504 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev); 505 506 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4)); 507 rt = ip_route_output_key_hash(net, fl4, skb_in); 508 if (IS_ERR(rt)) 509 return rt; 510 511 /* No need to clone since we're just using its address. */ 512 rt2 = rt; 513 514 dst = xfrm_lookup(net, &rt->dst, 515 flowi4_to_flowi(fl4), NULL, 0); 516 rt = dst_rtable(dst); 517 if (!IS_ERR(dst)) { 518 if (rt != rt2) 519 return rt; 520 if (inet_addr_type_dev_table(net, route_lookup_dev, 521 fl4->daddr) == RTN_LOCAL) 522 return rt; 523 } else if (PTR_ERR(dst) == -EPERM) { 524 rt = NULL; 525 } else { 526 return rt; 527 } 528 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET); 529 if (err) 530 goto relookup_failed; 531 532 if (inet_addr_type_dev_table(net, route_lookup_dev, 533 fl4_dec.saddr) == RTN_LOCAL) { 534 rt2 = __ip_route_output_key(net, &fl4_dec); 535 if (IS_ERR(rt2)) 536 err = PTR_ERR(rt2); 537 } else { 538 struct flowi4 fl4_2 = {}; 539 unsigned long orefdst; 540 541 fl4_2.daddr = fl4_dec.saddr; 542 rt2 = ip_route_output_key(net, &fl4_2); 543 if (IS_ERR(rt2)) { 544 err = PTR_ERR(rt2); 545 goto relookup_failed; 546 } 547 /* Ugh! */ 548 orefdst = skb_dstref_steal(skb_in); 549 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr, 550 dscp, rt2->dst.dev) ? -EINVAL : 0; 551 552 dst_release(&rt2->dst); 553 rt2 = skb_rtable(skb_in); 554 /* steal dst entry from skb_in, don't drop refcnt */ 555 skb_dstref_steal(skb_in); 556 skb_dstref_restore(skb_in, orefdst); 557 } 558 559 if (err) 560 goto relookup_failed; 561 562 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL, 563 XFRM_LOOKUP_ICMP); 564 rt2 = dst_rtable(dst2); 565 if (!IS_ERR(dst2)) { 566 dst_release(&rt->dst); 567 memcpy(fl4, &fl4_dec, sizeof(*fl4)); 568 rt = rt2; 569 } else if (PTR_ERR(dst2) == -EPERM) { 570 if (rt) 571 dst_release(&rt->dst); 572 return rt2; 573 } else { 574 err = PTR_ERR(dst2); 575 goto relookup_failed; 576 } 577 return rt; 578 579 relookup_failed: 580 if (rt) 581 return rt; 582 return ERR_PTR(err); 583 } 584 585 /* 586 * Send an ICMP message in response to a situation 587 * 588 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. 589 * MAY send more (we do). 590 * MUST NOT change this header information. 591 * MUST NOT reply to a multicast/broadcast IP address. 592 * MUST NOT reply to a multicast/broadcast MAC address. 593 * MUST reply to only the first fragment. 594 */ 595 596 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, 597 const struct inet_skb_parm *parm) 598 { 599 struct iphdr *iph; 600 int room; 601 struct icmp_bxm icmp_param; 602 struct rtable *rt = skb_rtable(skb_in); 603 bool apply_ratelimit = false; 604 struct ipcm_cookie ipc; 605 struct flowi4 fl4; 606 __be32 saddr; 607 u8 tos; 608 u32 mark; 609 struct net *net; 610 struct sock *sk; 611 612 if (!rt) 613 return; 614 615 rcu_read_lock(); 616 617 if (rt->dst.dev) 618 net = dev_net_rcu(rt->dst.dev); 619 else if (skb_in->dev) 620 net = dev_net_rcu(skb_in->dev); 621 else 622 goto out; 623 624 /* 625 * Find the original header. It is expected to be valid, of course. 626 * Check this, icmp_send is called from the most obscure devices 627 * sometimes. 628 */ 629 iph = ip_hdr(skb_in); 630 631 if ((u8 *)iph < skb_in->head || 632 (skb_network_header(skb_in) + sizeof(*iph)) > 633 skb_tail_pointer(skb_in)) 634 goto out; 635 636 /* 637 * No replies to physical multicast/broadcast 638 */ 639 if (skb_in->pkt_type != PACKET_HOST) 640 goto out; 641 642 /* 643 * Now check at the protocol level 644 */ 645 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) 646 goto out; 647 648 /* 649 * Only reply to fragment 0. We byte re-order the constant 650 * mask for efficiency. 651 */ 652 if (iph->frag_off & htons(IP_OFFSET)) 653 goto out; 654 655 /* 656 * If we send an ICMP error to an ICMP error a mess would result.. 657 */ 658 if (icmp_pointers[type].error) { 659 /* 660 * We are an error, check if we are replying to an 661 * ICMP error 662 */ 663 if (iph->protocol == IPPROTO_ICMP) { 664 u8 _inner_type, *itp; 665 666 itp = skb_header_pointer(skb_in, 667 skb_network_header(skb_in) + 668 (iph->ihl << 2) + 669 offsetof(struct icmphdr, 670 type) - 671 skb_in->data, 672 sizeof(_inner_type), 673 &_inner_type); 674 if (!itp) 675 goto out; 676 677 /* 678 * Assume any unknown ICMP type is an error. This 679 * isn't specified by the RFC, but think about it.. 680 */ 681 if (*itp > NR_ICMP_TYPES || 682 icmp_pointers[*itp].error) 683 goto out; 684 } 685 } 686 687 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */ 688 local_bh_disable(); 689 690 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless 691 * incoming dev is loopback. If outgoing dev change to not be 692 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow) 693 */ 694 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) && 695 !icmpv4_global_allow(net, type, code, &apply_ratelimit)) 696 goto out_bh_enable; 697 698 sk = icmp_xmit_lock(net); 699 if (!sk) 700 goto out_bh_enable; 701 702 /* 703 * Construct source address and options. 704 */ 705 706 saddr = iph->daddr; 707 if (!(rt->rt_flags & RTCF_LOCAL)) { 708 struct net_device *dev = NULL; 709 710 rcu_read_lock(); 711 if (rt_is_input_route(rt) && 712 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)) 713 dev = dev_get_by_index_rcu(net, parm->iif ? parm->iif : 714 inet_iif(skb_in)); 715 716 if (dev) 717 saddr = inet_select_addr(dev, iph->saddr, 718 RT_SCOPE_LINK); 719 else 720 saddr = 0; 721 rcu_read_unlock(); 722 } 723 724 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) | 725 IPTOS_PREC_INTERNETCONTROL) : 726 iph->tos; 727 mark = IP4_REPLY_MARK(net, skb_in->mark); 728 729 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, 730 &parm->opt)) 731 goto out_unlock; 732 733 734 /* 735 * Prepare data for ICMP header. 736 */ 737 738 icmp_param.data.icmph.type = type; 739 icmp_param.data.icmph.code = code; 740 icmp_param.data.icmph.un.gateway = info; 741 icmp_param.data.icmph.checksum = 0; 742 icmp_param.skb = skb_in; 743 icmp_param.offset = skb_network_offset(skb_in); 744 ipcm_init(&ipc); 745 ipc.tos = tos; 746 ipc.addr = iph->saddr; 747 ipc.opt = &icmp_param.replyopts.opt; 748 ipc.sockc.mark = mark; 749 750 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, 751 inet_dsfield_to_dscp(tos), mark, type, code, 752 &icmp_param); 753 if (IS_ERR(rt)) 754 goto out_unlock; 755 756 /* peer icmp_ratelimit */ 757 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit)) 758 goto ende; 759 760 /* RFC says return as much as we can without exceeding 576 bytes. */ 761 762 room = dst_mtu(&rt->dst); 763 if (room > 576) 764 room = 576; 765 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; 766 room -= sizeof(struct icmphdr); 767 /* Guard against tiny mtu. We need to include at least one 768 * IP network header for this message to make any sense. 769 */ 770 if (room <= (int)sizeof(struct iphdr)) 771 goto ende; 772 773 icmp_param.data_len = skb_in->len - icmp_param.offset; 774 if (icmp_param.data_len > room) 775 icmp_param.data_len = room; 776 icmp_param.head_len = sizeof(struct icmphdr); 777 778 /* if we don't have a source address at this point, fall back to the 779 * dummy address instead of sending out a packet with a source address 780 * of 0.0.0.0 781 */ 782 if (!fl4.saddr) 783 fl4.saddr = htonl(INADDR_DUMMY); 784 785 trace_icmp_send(skb_in, type, code); 786 787 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt); 788 ende: 789 ip_rt_put(rt); 790 out_unlock: 791 icmp_xmit_unlock(sk); 792 out_bh_enable: 793 local_bh_enable(); 794 out: 795 rcu_read_unlock(); 796 } 797 EXPORT_SYMBOL(__icmp_send); 798 799 #if IS_ENABLED(CONFIG_NF_NAT) 800 #include <net/netfilter/nf_conntrack.h> 801 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) 802 { 803 struct sk_buff *cloned_skb = NULL; 804 enum ip_conntrack_info ctinfo; 805 enum ip_conntrack_dir dir; 806 struct inet_skb_parm parm; 807 struct nf_conn *ct; 808 __be32 orig_ip; 809 810 memset(&parm, 0, sizeof(parm)); 811 ct = nf_ct_get(skb_in, &ctinfo); 812 if (!ct || !(READ_ONCE(ct->status) & IPS_NAT_MASK)) { 813 __icmp_send(skb_in, type, code, info, &parm); 814 return; 815 } 816 817 if (skb_shared(skb_in)) 818 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC); 819 820 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head || 821 (skb_network_header(skb_in) + sizeof(struct iphdr)) > 822 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in, 823 skb_network_offset(skb_in) + sizeof(struct iphdr)))) 824 goto out; 825 826 orig_ip = ip_hdr(skb_in)->saddr; 827 dir = CTINFO2DIR(ctinfo); 828 ip_hdr(skb_in)->saddr = ct->tuplehash[dir].tuple.src.u3.ip; 829 __icmp_send(skb_in, type, code, info, &parm); 830 ip_hdr(skb_in)->saddr = orig_ip; 831 out: 832 consume_skb(cloned_skb); 833 } 834 EXPORT_SYMBOL(icmp_ndo_send); 835 #endif 836 837 static void icmp_socket_deliver(struct sk_buff *skb, u32 info) 838 { 839 const struct iphdr *iph = (const struct iphdr *)skb->data; 840 const struct net_protocol *ipprot; 841 int protocol = iph->protocol; 842 843 /* Checkin full IP header plus 8 bytes of protocol to 844 * avoid additional coding at protocol handlers. 845 */ 846 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) { 847 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 848 return; 849 } 850 851 raw_icmp_error(skb, protocol, info); 852 853 ipprot = rcu_dereference(inet_protos[protocol]); 854 if (ipprot && ipprot->err_handler) 855 ipprot->err_handler(skb, info); 856 } 857 858 static bool icmp_tag_validation(int proto) 859 { 860 bool ok; 861 862 rcu_read_lock(); 863 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation; 864 rcu_read_unlock(); 865 return ok; 866 } 867 868 /* 869 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and 870 * ICMP_PARAMETERPROB. 871 */ 872 873 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb) 874 { 875 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; 876 const struct iphdr *iph; 877 struct icmphdr *icmph; 878 struct net *net; 879 u32 info = 0; 880 881 net = skb_dst_dev_net_rcu(skb); 882 883 /* 884 * Incomplete header ? 885 * Only checks for the IP header, there should be an 886 * additional check for longer headers in upper levels. 887 */ 888 889 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 890 goto out_err; 891 892 icmph = icmp_hdr(skb); 893 iph = (const struct iphdr *)skb->data; 894 895 if (iph->ihl < 5) { /* Mangled header, drop. */ 896 reason = SKB_DROP_REASON_IP_INHDR; 897 goto out_err; 898 } 899 900 switch (icmph->type) { 901 case ICMP_DEST_UNREACH: 902 switch (icmph->code & 15) { 903 case ICMP_NET_UNREACH: 904 case ICMP_HOST_UNREACH: 905 case ICMP_PROT_UNREACH: 906 case ICMP_PORT_UNREACH: 907 break; 908 case ICMP_FRAG_NEEDED: 909 /* for documentation of the ip_no_pmtu_disc 910 * values please see 911 * Documentation/networking/ip-sysctl.rst 912 */ 913 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) { 914 default: 915 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n", 916 &iph->daddr); 917 break; 918 case 2: 919 goto out; 920 case 3: 921 if (!icmp_tag_validation(iph->protocol)) 922 goto out; 923 fallthrough; 924 case 0: 925 info = ntohs(icmph->un.frag.mtu); 926 } 927 break; 928 case ICMP_SR_FAILED: 929 net_dbg_ratelimited("%pI4: Source Route Failed\n", 930 &iph->daddr); 931 break; 932 default: 933 break; 934 } 935 if (icmph->code > NR_ICMP_UNREACH) 936 goto out; 937 break; 938 case ICMP_PARAMETERPROB: 939 info = ntohl(icmph->un.gateway) >> 24; 940 break; 941 case ICMP_TIME_EXCEEDED: 942 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS); 943 if (icmph->code == ICMP_EXC_FRAGTIME) 944 goto out; 945 break; 946 } 947 948 /* 949 * Throw it at our lower layers 950 * 951 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed 952 * header. 953 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the 954 * transport layer. 955 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to 956 * transport layer. 957 */ 958 959 /* 960 * Check the other end isn't violating RFC 1122. Some routers send 961 * bogus responses to broadcast frames. If you see this message 962 * first check your netmask matches at both ends, if it does then 963 * get the other vendor to fix their kit. 964 */ 965 966 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) && 967 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) { 968 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n", 969 &ip_hdr(skb)->saddr, 970 icmph->type, icmph->code, 971 &iph->daddr, skb->dev->name); 972 goto out; 973 } 974 975 icmp_socket_deliver(skb, info); 976 977 out: 978 return reason; 979 out_err: 980 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 981 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED; 982 } 983 984 985 /* 986 * Handle ICMP_REDIRECT. 987 */ 988 989 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb) 990 { 991 if (skb->len < sizeof(struct iphdr)) { 992 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS); 993 return SKB_DROP_REASON_PKT_TOO_SMALL; 994 } 995 996 if (!pskb_may_pull(skb, sizeof(struct iphdr))) { 997 /* there aught to be a stat */ 998 return SKB_DROP_REASON_NOMEM; 999 } 1000 1001 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway)); 1002 return SKB_NOT_DROPPED_YET; 1003 } 1004 1005 /* 1006 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests. 1007 * 1008 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo 1009 * requests. 1010 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be 1011 * included in the reply. 1012 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring 1013 * echo requests, MUST have default=NOT. 1014 * RFC 8335: 8 MUST have a config option to enable/disable ICMP 1015 * Extended Echo Functionality, MUST be disabled by default 1016 * See also WRT handling of options once they are done and working. 1017 */ 1018 1019 static enum skb_drop_reason icmp_echo(struct sk_buff *skb) 1020 { 1021 struct icmp_bxm icmp_param; 1022 struct net *net; 1023 1024 net = skb_dst_dev_net_rcu(skb); 1025 /* should there be an ICMP stat for ignored echos? */ 1026 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all)) 1027 return SKB_NOT_DROPPED_YET; 1028 1029 icmp_param.data.icmph = *icmp_hdr(skb); 1030 icmp_param.skb = skb; 1031 icmp_param.offset = 0; 1032 icmp_param.data_len = skb->len; 1033 icmp_param.head_len = sizeof(struct icmphdr); 1034 1035 if (icmp_param.data.icmph.type == ICMP_ECHO) 1036 icmp_param.data.icmph.type = ICMP_ECHOREPLY; 1037 else if (!icmp_build_probe(skb, &icmp_param.data.icmph)) 1038 return SKB_NOT_DROPPED_YET; 1039 1040 icmp_reply(&icmp_param, skb); 1041 return SKB_NOT_DROPPED_YET; 1042 } 1043 1044 /* Helper for icmp_echo and icmpv6_echo_reply. 1045 * Searches for net_device that matches PROBE interface identifier 1046 * and builds PROBE reply message in icmphdr. 1047 * 1048 * Returns false if PROBE responses are disabled via sysctl 1049 */ 1050 1051 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 1052 { 1053 struct net *net = dev_net_rcu(skb->dev); 1054 struct icmp_ext_hdr *ext_hdr, _ext_hdr; 1055 struct icmp_ext_echo_iio *iio, _iio; 1056 struct inet6_dev *in6_dev; 1057 struct in_device *in_dev; 1058 struct net_device *dev; 1059 char buff[IFNAMSIZ]; 1060 u16 ident_len; 1061 u8 status; 1062 1063 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 1064 return false; 1065 1066 /* We currently only support probing interfaces on the proxy node 1067 * Check to ensure L-bit is set 1068 */ 1069 if (!(ntohs(icmphdr->un.echo.sequence) & 1)) 1070 return false; 1071 /* Clear status bits in reply message */ 1072 icmphdr->un.echo.sequence &= htons(0xFF00); 1073 if (icmphdr->type == ICMP_EXT_ECHO) 1074 icmphdr->type = ICMP_EXT_ECHOREPLY; 1075 else 1076 icmphdr->type = ICMPV6_EXT_ECHO_REPLY; 1077 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr); 1078 /* Size of iio is class_type dependent. 1079 * Only check header here and assign length based on ctype in the switch statement 1080 */ 1081 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio); 1082 if (!ext_hdr || !iio) 1083 goto send_mal_query; 1084 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) || 1085 ntohs(iio->extobj_hdr.length) > sizeof(_iio)) 1086 goto send_mal_query; 1087 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr); 1088 iio = skb_header_pointer(skb, sizeof(_ext_hdr), 1089 sizeof(iio->extobj_hdr) + ident_len, &_iio); 1090 if (!iio) 1091 goto send_mal_query; 1092 1093 status = 0; 1094 dev = NULL; 1095 switch (iio->extobj_hdr.class_type) { 1096 case ICMP_EXT_ECHO_CTYPE_NAME: 1097 if (ident_len >= IFNAMSIZ) 1098 goto send_mal_query; 1099 memset(buff, 0, sizeof(buff)); 1100 memcpy(buff, &iio->ident.name, ident_len); 1101 dev = dev_get_by_name(net, buff); 1102 break; 1103 case ICMP_EXT_ECHO_CTYPE_INDEX: 1104 if (ident_len != sizeof(iio->ident.ifindex)) 1105 goto send_mal_query; 1106 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex)); 1107 break; 1108 case ICMP_EXT_ECHO_CTYPE_ADDR: 1109 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) || 1110 ident_len != sizeof(iio->ident.addr.ctype3_hdr) + 1111 iio->ident.addr.ctype3_hdr.addrlen) 1112 goto send_mal_query; 1113 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) { 1114 case ICMP_AFI_IP: 1115 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr)) 1116 goto send_mal_query; 1117 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr); 1118 break; 1119 #if IS_ENABLED(CONFIG_IPV6) 1120 case ICMP_AFI_IP6: 1121 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) 1122 goto send_mal_query; 1123 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); 1124 dev_hold(dev); 1125 break; 1126 #endif 1127 default: 1128 goto send_mal_query; 1129 } 1130 break; 1131 default: 1132 goto send_mal_query; 1133 } 1134 if (!dev) { 1135 icmphdr->code = ICMP_EXT_CODE_NO_IF; 1136 return true; 1137 } 1138 /* Fill bits in reply message */ 1139 if (dev->flags & IFF_UP) 1140 status |= ICMP_EXT_ECHOREPLY_ACTIVE; 1141 1142 in_dev = __in_dev_get_rcu(dev); 1143 if (in_dev && rcu_access_pointer(in_dev->ifa_list)) 1144 status |= ICMP_EXT_ECHOREPLY_IPV4; 1145 1146 in6_dev = __in6_dev_get(dev); 1147 if (in6_dev && !list_empty(&in6_dev->addr_list)) 1148 status |= ICMP_EXT_ECHOREPLY_IPV6; 1149 1150 dev_put(dev); 1151 icmphdr->un.echo.sequence |= htons(status); 1152 return true; 1153 send_mal_query: 1154 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY; 1155 return true; 1156 } 1157 EXPORT_SYMBOL_GPL(icmp_build_probe); 1158 1159 /* 1160 * Handle ICMP Timestamp requests. 1161 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. 1162 * SHOULD be in the kernel for minimum random latency. 1163 * MUST be accurate to a few minutes. 1164 * MUST be updated at least at 15Hz. 1165 */ 1166 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb) 1167 { 1168 struct icmp_bxm icmp_param; 1169 /* 1170 * Too short. 1171 */ 1172 if (skb->len < 4) 1173 goto out_err; 1174 1175 /* 1176 * Fill in the current time as ms since midnight UT: 1177 */ 1178 icmp_param.data.times[1] = inet_current_timestamp(); 1179 icmp_param.data.times[2] = icmp_param.data.times[1]; 1180 1181 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)); 1182 1183 icmp_param.data.icmph = *icmp_hdr(skb); 1184 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; 1185 icmp_param.data.icmph.code = 0; 1186 icmp_param.skb = skb; 1187 icmp_param.offset = 0; 1188 icmp_param.data_len = 0; 1189 icmp_param.head_len = sizeof(struct icmphdr) + 12; 1190 icmp_reply(&icmp_param, skb); 1191 return SKB_NOT_DROPPED_YET; 1192 1193 out_err: 1194 __ICMP_INC_STATS(skb_dst_dev_net_rcu(skb), ICMP_MIB_INERRORS); 1195 return SKB_DROP_REASON_PKT_TOO_SMALL; 1196 } 1197 1198 static enum skb_drop_reason icmp_discard(struct sk_buff *skb) 1199 { 1200 /* pretend it was a success */ 1201 return SKB_NOT_DROPPED_YET; 1202 } 1203 1204 /* 1205 * Deal with incoming ICMP packets. 1206 */ 1207 int icmp_rcv(struct sk_buff *skb) 1208 { 1209 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 1210 struct rtable *rt = skb_rtable(skb); 1211 struct net *net = dev_net_rcu(rt->dst.dev); 1212 struct icmphdr *icmph; 1213 1214 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { 1215 struct sec_path *sp = skb_sec_path(skb); 1216 int nh; 1217 1218 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 1219 XFRM_STATE_ICMP)) { 1220 reason = SKB_DROP_REASON_XFRM_POLICY; 1221 goto drop; 1222 } 1223 1224 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) 1225 goto drop; 1226 1227 nh = skb_network_offset(skb); 1228 skb_set_network_header(skb, sizeof(*icmph)); 1229 1230 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, 1231 skb)) { 1232 reason = SKB_DROP_REASON_XFRM_POLICY; 1233 goto drop; 1234 } 1235 1236 skb_set_network_header(skb, nh); 1237 } 1238 1239 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS); 1240 1241 if (skb_checksum_simple_validate(skb)) 1242 goto csum_error; 1243 1244 if (!pskb_pull(skb, sizeof(*icmph))) 1245 goto error; 1246 1247 icmph = icmp_hdr(skb); 1248 1249 ICMPMSGIN_INC_STATS(net, icmph->type); 1250 1251 /* Check for ICMP Extended Echo (PROBE) messages */ 1252 if (icmph->type == ICMP_EXT_ECHO) { 1253 /* We can't use icmp_pointers[].handler() because it is an array of 1254 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42. 1255 */ 1256 reason = icmp_echo(skb); 1257 goto reason_check; 1258 } 1259 1260 /* 1261 * Parse the ICMP message 1262 */ 1263 1264 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { 1265 /* 1266 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be 1267 * silently ignored (we let user decide with a sysctl). 1268 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently 1269 * discarded if to broadcast/multicast. 1270 */ 1271 if ((icmph->type == ICMP_ECHO || 1272 icmph->type == ICMP_TIMESTAMP) && 1273 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) { 1274 reason = SKB_DROP_REASON_INVALID_PROTO; 1275 goto error; 1276 } 1277 if (icmph->type != ICMP_ECHO && 1278 icmph->type != ICMP_TIMESTAMP && 1279 icmph->type != ICMP_ADDRESS && 1280 icmph->type != ICMP_ADDRESSREPLY) { 1281 reason = SKB_DROP_REASON_INVALID_PROTO; 1282 goto error; 1283 } 1284 } 1285 1286 if (icmph->type == ICMP_EXT_ECHOREPLY || 1287 icmph->type == ICMP_ECHOREPLY) { 1288 reason = ping_rcv(skb); 1289 return reason ? NET_RX_DROP : NET_RX_SUCCESS; 1290 } 1291 1292 /* 1293 * 18 is the highest 'known' ICMP type. Anything else is a mystery 1294 * 1295 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently 1296 * discarded. 1297 */ 1298 if (icmph->type > NR_ICMP_TYPES) { 1299 reason = SKB_DROP_REASON_UNHANDLED_PROTO; 1300 goto error; 1301 } 1302 1303 reason = icmp_pointers[icmph->type].handler(skb); 1304 reason_check: 1305 if (!reason) { 1306 consume_skb(skb); 1307 return NET_RX_SUCCESS; 1308 } 1309 1310 drop: 1311 kfree_skb_reason(skb, reason); 1312 return NET_RX_DROP; 1313 csum_error: 1314 reason = SKB_DROP_REASON_ICMP_CSUM; 1315 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS); 1316 error: 1317 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS); 1318 goto drop; 1319 } 1320 1321 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off) 1322 { 1323 struct icmp_extobj_hdr *objh, _objh; 1324 struct icmp_ext_hdr *exth, _exth; 1325 u16 olen; 1326 1327 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth); 1328 if (!exth) 1329 return false; 1330 if (exth->version != 2) 1331 return true; 1332 1333 if (exth->checksum && 1334 csum_fold(skb_checksum(skb, off, skb->len - off, 0))) 1335 return false; 1336 1337 off += sizeof(_exth); 1338 while (off < skb->len) { 1339 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh); 1340 if (!objh) 1341 return false; 1342 1343 olen = ntohs(objh->length); 1344 if (olen < sizeof(_objh)) 1345 return false; 1346 1347 off += olen; 1348 if (off > skb->len) 1349 return false; 1350 } 1351 1352 return true; 1353 } 1354 1355 void ip_icmp_error_rfc4884(const struct sk_buff *skb, 1356 struct sock_ee_data_rfc4884 *out, 1357 int thlen, int off) 1358 { 1359 int hlen; 1360 1361 /* original datagram headers: end of icmph to payload (skb->data) */ 1362 hlen = -skb_transport_offset(skb) - thlen; 1363 1364 /* per rfc 4884: minimal datagram length of 128 bytes */ 1365 if (off < 128 || off < hlen) 1366 return; 1367 1368 /* kernel has stripped headers: return payload offset in bytes */ 1369 off -= hlen; 1370 if (off + sizeof(struct icmp_ext_hdr) > skb->len) 1371 return; 1372 1373 out->len = off; 1374 1375 if (!ip_icmp_error_rfc4884_validate(skb, off)) 1376 out->flags |= SO_EE_RFC4884_FLAG_INVALID; 1377 } 1378 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884); 1379 1380 int icmp_err(struct sk_buff *skb, u32 info) 1381 { 1382 struct iphdr *iph = (struct iphdr *)skb->data; 1383 int offset = iph->ihl<<2; 1384 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset); 1385 struct net *net = dev_net_rcu(skb->dev); 1386 int type = icmp_hdr(skb)->type; 1387 int code = icmp_hdr(skb)->code; 1388 1389 /* 1390 * Use ping_err to handle all icmp errors except those 1391 * triggered by ICMP_ECHOREPLY which sent from kernel. 1392 */ 1393 if (icmph->type != ICMP_ECHOREPLY) { 1394 ping_err(skb, offset, info); 1395 return 0; 1396 } 1397 1398 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) 1399 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP); 1400 else if (type == ICMP_REDIRECT) 1401 ipv4_redirect(skb, net, 0, IPPROTO_ICMP); 1402 1403 return 0; 1404 } 1405 1406 /* 1407 * This table is the definition of how we handle ICMP. 1408 */ 1409 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { 1410 [ICMP_ECHOREPLY] = { 1411 .handler = ping_rcv, 1412 }, 1413 [1] = { 1414 .handler = icmp_discard, 1415 .error = 1, 1416 }, 1417 [2] = { 1418 .handler = icmp_discard, 1419 .error = 1, 1420 }, 1421 [ICMP_DEST_UNREACH] = { 1422 .handler = icmp_unreach, 1423 .error = 1, 1424 }, 1425 [ICMP_SOURCE_QUENCH] = { 1426 .handler = icmp_unreach, 1427 .error = 1, 1428 }, 1429 [ICMP_REDIRECT] = { 1430 .handler = icmp_redirect, 1431 .error = 1, 1432 }, 1433 [6] = { 1434 .handler = icmp_discard, 1435 .error = 1, 1436 }, 1437 [7] = { 1438 .handler = icmp_discard, 1439 .error = 1, 1440 }, 1441 [ICMP_ECHO] = { 1442 .handler = icmp_echo, 1443 }, 1444 [9] = { 1445 .handler = icmp_discard, 1446 .error = 1, 1447 }, 1448 [10] = { 1449 .handler = icmp_discard, 1450 .error = 1, 1451 }, 1452 [ICMP_TIME_EXCEEDED] = { 1453 .handler = icmp_unreach, 1454 .error = 1, 1455 }, 1456 [ICMP_PARAMETERPROB] = { 1457 .handler = icmp_unreach, 1458 .error = 1, 1459 }, 1460 [ICMP_TIMESTAMP] = { 1461 .handler = icmp_timestamp, 1462 }, 1463 [ICMP_TIMESTAMPREPLY] = { 1464 .handler = icmp_discard, 1465 }, 1466 [ICMP_INFO_REQUEST] = { 1467 .handler = icmp_discard, 1468 }, 1469 [ICMP_INFO_REPLY] = { 1470 .handler = icmp_discard, 1471 }, 1472 [ICMP_ADDRESS] = { 1473 .handler = icmp_discard, 1474 }, 1475 [ICMP_ADDRESSREPLY] = { 1476 .handler = icmp_discard, 1477 }, 1478 }; 1479 1480 static int __net_init icmp_sk_init(struct net *net) 1481 { 1482 /* Control parameters for ECHO replies. */ 1483 net->ipv4.sysctl_icmp_echo_ignore_all = 0; 1484 net->ipv4.sysctl_icmp_echo_enable_probe = 0; 1485 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; 1486 1487 /* Control parameter - ignore bogus broadcast responses? */ 1488 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; 1489 1490 /* 1491 * Configurable global rate limit. 1492 * 1493 * ratelimit defines tokens/packet consumed for dst->rate_token 1494 * bucket ratemask defines which icmp types are ratelimited by 1495 * setting it's bit position. 1496 * 1497 * default: 1498 * dest unreachable (3), source quench (4), 1499 * time exceeded (11), parameter problem (12) 1500 */ 1501 1502 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; 1503 net->ipv4.sysctl_icmp_ratemask = 0x1818; 1504 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; 1505 net->ipv4.sysctl_icmp_msgs_per_sec = 1000; 1506 net->ipv4.sysctl_icmp_msgs_burst = 50; 1507 1508 return 0; 1509 } 1510 1511 static struct pernet_operations __net_initdata icmp_sk_ops = { 1512 .init = icmp_sk_init, 1513 }; 1514 1515 int __init icmp_init(void) 1516 { 1517 int err, i; 1518 1519 for_each_possible_cpu(i) { 1520 struct sock *sk; 1521 1522 err = inet_ctl_sock_create(&sk, PF_INET, 1523 SOCK_RAW, IPPROTO_ICMP, &init_net); 1524 if (err < 0) 1525 return err; 1526 1527 per_cpu(ipv4_icmp_sk, i) = sk; 1528 1529 /* Enough space for 2 64K ICMP packets, including 1530 * sk_buff/skb_shared_info struct overhead. 1531 */ 1532 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1533 1534 /* 1535 * Speedup sock_wfree() 1536 */ 1537 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 1538 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; 1539 } 1540 return register_pernet_subsys(&icmp_sk_ops); 1541 } 1542